Structure for loading substrate in substrate bonding apparatus for fabricating liquid crystal display device

ABSTRACT

A substrate bonding apparatus for use in fabricating LCD devices substantially prevents substrates held to upper stages from sagging. The substrate bonding apparatus may, for example, include upper and lower stages having a plurality of passages for holding respective substrates; suction force applying means having one end mounted within each passage for transmitting a suction force to operably proximate portions of a substrate, wherein the one end of the suction force applying means is projectable from within each passage to a predetermined distance from the stage; and a vacuum pump for providing a suction force to the suction force applying means.

This application is a divisional application of 10/700,475 filed Nov. 5,2003, now U.S. Pat. No. 7,314,535, which claims the benefit of KoreanApplication No. P2002-68822 filed Nov. 7, 2002, which are incorporatedby reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate bonding apparatus forfabricating liquid crystal display (LCD) devices fabricated according toa liquid crystal dispensing method. More particularly, the presentinvention relates to a structure for securing substrates to stages(e.g., upper stages) of a substrate bonding apparatus.

2. Discussion of the Related Art

As the development of diverse types of information devices proliferateand become available to consumers, demands on the types of displays usedby the information devices have increased. To meet such demands, manytypes of flat display devices including Liquid Crystal Display (LCD)devices, Plasma Display Panels (PDP), Electro Luminescent Display (ELD),Vacuum Fluorescent Display (VFD), etc., are currently being developedand, in some instances, actually employed as displays.

Among the various flat displays, LCD devices are commonly used asportable display devices. Due to their beneficial characteristics suchas excellent picture quality (e.g., high resolution and luminance),light weight, thin profile, large display area, and low powerconsumption, LCD devices are commonly used in applications previouslydominated by Cathode Ray Tubes (CRTs). Accordingly, LCD devices arecommonly used in applications such as monitors of notebook computers,monitors of computers, and as TVs capable of receiving and displayingbroadcasting signals.

Generally, LCD devices are fabricated using liquid crystal injection orliquid crystal dispensing methods. According to the liquid crystalinjection method, opposing substrates are bonded together in a vacuumvia a patterned sealant material formed on one of the substrates,wherein the patterned sealant material includes a liquid crystalinjection hole. After being bonded, liquid crystal material is injectedthrough the liquid crystal injection hole and between the bondsubstrates. Japanese Laid Open Patent Nos. 2000-284295 (Japanese PatentApplication 1999-089612) and 2001-005405 (Japanese Patent Application1999-172903) can be understood to teach a related art liquid crystaldispensing method wherein first and second substrates are provided andliquid crystal material is dispensed onto the first substrate.Subsequently, the first and second substrates are arranged to opposeeach other, wherein the dispensed liquid crystal material is arrangedbetween the opposing substrates. Lastly, the opposing substrates arebonded together in a vacuum.

FIG. 1 illustrates a related art substrate bonding apparatus forfabricating LCD devices using the liquid crystal dispensing method.

Referring to FIG. 1, a related art substrate bonding apparatus includesa frame 10, an upper stage 21, a lower stage 22, a sealant dispenser(not shown), a liquid crystal dispenser 30, an upper chamber unit 31, alower chamber unit 32, chamber moving means, and stage moving means. Thesealant dispenser and liquid crystal dispenser 30 are mounted at sidepositions of the frame 10. The upper chamber unit 31 can be selectivelyjoined to the lower chamber unit 32. The chamber moving means includes adriving motor 40 for moving the lower chamber unit 32 to position S1,where sealant material and liquid crystal material can be dispensed ontoa substrate, and to position S2, where substrates can be bondedtogether. The stage moving means includes a driving motor 50 for raisingand lowering the upper stage 21 before, during, and after the substrateshave been bonded. Having described the related art substrate bondingapparatus above, the process by which the related art substrate bondingapparatus fabricates an LCD device will now be described in greaterdetail below.

To fabricate an LCD device using the related art substrate bondingapparatus described above, a first substrate 51 is held by the upperstage 21 while a second substrate 52 is held by the lower stage 22, asshown in FIG. 1. Next, the chamber moving means moves the lower chamberunit 32, supporting the lower stage 22, to the position S1.Subsequently, sealant material and liquid crystal material are dispensedonto the second substrate 52 held by the lower stage 22. After sealantmaterial and liquid crystal material are dispensed onto the secondsubstrate 52, the chamber moving means moves the lower chamber unit 32to position S2, as shown in FIG. 2, whereby the first and secondsubstrates 51 and 52, respectively, can be bonded together. With thelower chamber unit 32 at position S2, the chamber moving means joins theupper chamber unit 31 to the lower chamber unit 32. Upon being joined,the upper chamber unit 31 and the lower chamber unit 32 define aninterior space that encloses the upper and lower stages 21 and 22,respectively. Using a vacuum means (not shown), the interior space isevacuated to create a vacuum. Within the evacuated interior space, thestage moving means lowers the upper stage 21 such that the firstsubstrate 51, held by the upper stage 21, moves toward the secondsubstrate 52, held by the lower stage 22. As the upper stage 21descends, the first and second substrates 51 and 52, respectively,become bonded to each other, thereby completing fabrication of the LCDdevice.

Fabricating LCD devices using the related art substrate bondingapparatus, however, is disadvantageous because the upper stage 21 holdsthe first substrate 51 by transmitting a suction force to operablyproximate portions of the first substrate 51. Due to the dimensions andweight of the first substrate 51, some portions of the first substrate51 may not be operably proximate the upper stage 21. For example,peripheral portions of the first substrate 51 may be sufficiently closeto the upper stage 21 (i.e., operably proximate) to be affected by thetransmitted suction force. However, due to the weight of the firstsubstrate 51, interior portions of the first substrate 51 may be spacedapart from the upper stage 51 (e.g., sag) by a distance which is outsidethe range (i.e., not operably proximate) in which the transmittedsuction force may affect the first substrate 51. Accordingly, the upperstage 21 may not effectively transmit a suction force to those portionsof the first substrate 51 that are not operably proximate to the upperstage 21.

Related art attempts to prevent the aforementioned sagging phenomenonfrom occurring have been met by increasing the suction force transmittedby upper stage 21 to the first substrate 51. However, the firstsubstrate 51 may become damaged if the transmitted suction force becomesexcessive. As display areas of LCD devices continues to increase,methods and apparatuses capable of safely and effectively transmittingsuction forces from upper stages to corresponding substrates must bedeveloped.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a structure forholding substrates to an upper stage of a substrate bonding apparatusused in fabricating LCD devices that substantially obviates one or moreproblems due to limitations and disadvantages of the related art.

An advantage of the present invention provides a structure for holdingsubstrates to upper stages of substrate bonding apparatuses used infabricating LCD devices, wherein the sagging phenomenon may besubstantially eliminated.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. These andother advantages of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, a structurefor holding substrates within a substrate bonding apparatus used infabricating LCD devices may, for example, include upper and lowerstages, wherein the upper and lower stages each include plurality ofpassages for holding substrates; suction force applying means fortransmitting a suction force to a respective substrate to thereby hold asubstrate to a respective stage, wherein the suction force applyingmeans includes one end arranged within each passage, wherein the end isprojectable outside each passage; and a vacuum pump for generating thesuction force.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIGS. 1 and 2 illustrate a related art substrate bonding apparatus usedin fabricating LCD devices;

FIG. 3 illustrates a structure for holding substrates within a substratebonding apparatus for fabricating LCD devices according to principles ofthe present invention; and

FIGS. 4 to 7 illustrate a method by which substrates may be held withina substrate bonding apparatus used in fabricating LCD devices accordingto principles of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIG. 3 illustrates a structure for holding substrates within a substratebonding apparatus used in fabricating LCD devices according toprinciples of the present invention.

Referring to FIG. 3, a structure for holding substrates within asubstrate bonding apparatus used in fabricating LCD devices may, forexample, include an upper stage 110, a lower stage 120, suction forceapplying means, a vacuum pump 140, and sensing means 150 for measuring adistance between a contact surface of the upper stage 110 and firstsubstrate 210 and a contact surface of the lower stage 120 and thesecond substrate 220.

According to principles of the present invention, the upper and lowerstages 110 and 120, respectively, may hold first and second substrates210 and 220, respectively, by transmitting suction forces to operablyproximate portions of substrates 210 and 220, respectively. In oneaspect of the present invention, a plurality of passages 111 and 121 maybe formed within stages 110 and 120, respectively, wherein each of thepassages 111 and 121 intersect with the contact surfaces of the upperand lower stages 110 and 120, respectively. In one aspect of the presentinvention, the passages may be, for example, cylindrically shaped. Inanother aspect of the present invention, the suction force applyingmeans may be arranged within each of the plurality of passages 111 and121 and may hold substrates 210 and 220, respectively, to upper andlower stages 110 and 120, respectively, by transmitting a vacuum suctionforce to operably proximate portions of the substrates 210 and 220,respectively.

According to the principles of the present invention, the suction forceapplying means may, for example, include a plurality of pads 131, aplurality of moving pipes 132, and a plurality of driving parts 133. Inone aspect of the present invention, each of the plurality of pads 131may include at least one vacuum hole 131 a for transmitting a suctionforce to the operably proximate portions of the substrates 210 and 220.In another aspect of the present invention, each of the plurality ofmoving pipes 132 may be in fluid communication with each vacuum hole 131a within a pad 131. In still another aspect of the present invention,each of the plurality of moving pipes 132 may raise or lower arespective pad 131 into and out of a respective one of the plurality ofpassages 111 and 121. Further, each of the plurality of moving pipes 132may be in fluid communication with the vacuum pump 140, wherein thevacuum pump may generate the aforementioned suction force. In stillanother aspect of the present invention, each of the plurality ofdriving parts 133 may be connected to a respective one of the movingpipes 132 for independently raising or lowering each respective movingpipe 132 within its respective passage 111 or 121.

According to the principles of the present invention, cross-sectionaldimensions of each pad 131 may substantially conform to cross-sectionaldimensions of the respective passages 111 and 121. In one aspect of thepresent invention, however, cross-sectional dimensions of each pad 131may be smaller than the cross-sectional dimensions of the respectivepassages 111 and 121. In one aspect of the present invention, eachmoving pipe 132 may include a first end and a second end, wherein thefirst end may be in fluid communication with each vacuum hole 131 awithin its respective pad 131, and wherein the second end may bearranged within each passage 111 and 121. Further, the second end may bein fluid communication with a connection pipe 141 of the vacuum pump140. In yet another aspect of the present invention, the second end ofeach moving pipe 132 may be moved (e.g., raised and/or lowered) within arespective passage 111 or 121 by the driving part 133.

According to the principles of the present invention, the driving part133 may, for example, be provided as an actuator wherein the moving pipe132 is an axis. In one aspect of the present invention, the driving part133 may, for example, be provided as a step motor or a linear motor,wherein the moving pipe 132 is the axis. It is appreciated, however,that the driving part 133 may be provided as substantially any mechanismsuitable for moving the moving pipe 132. The vacuum pump 140 maygenerate a suction force by pumping. The generated suction force may betransmitted to each pad 131 via a respective moving pipe 132. Thesensing means 150 may measure a distance between a contact surface ofthe upper stage 110 and first substrate 210 and a contact surface of thelower stage 120 and second substrate 220. In one aspect of the presentinvention, the sensing means 150 may be provided as an interval checksensor. Lastly, a plurality of vacuum holes 112 and 122 may be arrangedwithin stages 110 and 120, respectively, for transmitting the generatedsuction force generated by the vacuum pump 140 from the contact surfaceof the upper and lower stages 110 and 120, respectively, to operablyproximate portions of the substrates 210 and 220, respectively (e.g.,peripheral edges).

Having described the inventive structure for holding substrates in abonding apparatus used in fabricating LCD devices, the process by whichsubstrates may be held within a bonding apparatus in accordance with theprinciples of the present invention will now be described in greaterdetail below.

FIGS. 4 to 7 illustrate a method by which substrates are held within asubstrate bonding apparatus used in fabricating LCD devices according toprinciples of the present invention

Referring to FIG. 4, a loader 300 may be used to arrange a firstsubstrate 210 proximate a contact surface of the upper stage 110. In oneaspect of the present invention, sealant material may be arranged on asurface of the first substrate 210 opposite the contact surface of thefirst substrate 210. In another aspect of the present invention, theloader 300 may be provided with at least one finger 310 to minimize thedegree to which portions of the first substrate 210 sag with respect tothe contact surface of the upper stage 110. As shown in FIG. 4, however,portions of the first substrate 210 unsupported by fingers 310, maystill sag with respect to the contact surface of the upper stage 210.After portions of the first substrate (e.g., peripheral portions) arearranged operably proximate the contact surface of the upper stage 110,the vacuum pump 140 may be activated to generate a suction force that istransmitted by the vacuum holes 112 formed in the upper stage 110.Accordingly, the vacuum holes 112 transmit the generated suction forcefrom the contact surface of the upper stage 110 to hold the operablyproximate portions of the first substrate 210 against the contactsurface of the upper stage 110, as shown in FIG. 5.

Still referring to FIG. 5, portions of the first substrate 210 may notbe operably proximate to the contact surface of the upper stage 110(i.e., the first substrate 210 may sag with respect to the contactsurface of the upper stage 110) and may therefore not be affected by thesuction force transmitted by the vacuum holes 131 a.

Referring to FIG. 6, due to the sagging of the first substrate 210, eachdriving part 133 may be independently driven to lower respective ones ofthe moving pipes 132 a predetermined distance from the contact surfaceof the upper stage 110. Upon lowering the moving pipes 132, respectiveones of the vacuum holes 131 a may be arranged operably proximate thesagging portions of first substrate 210. In one aspect of the presentinvention, each moving pipe 132 may be lowered a predetermined distancein accordance with an output of the sensing means 150. After each movingpipe 132 has been lowered the predetermined distance, the suction force,generated by the vacuum pump 140, may be effectively transmitted fromthe vacuum hole 131 a of each pad 131 through each moving pipe 132 tothe sagging portions of the first substrate 210. As a result, portionsof the first substrate 210 previously found sagging with respect to thecontact surface of the upper stage 210 may be held to the projected pads131 by the transmitted suction force.

After the first substrate 210 is held to the pads 131, each driving part133 may be independently driven again to raise respective ones of themoving pipes 132 by a predetermined distance. In one aspect of thepresent invention, the moving pipes 132 may be raised such that a lowersurface of each of the pads 131 is substantially flush with the contactsurface of the upper stage 110. In other words, the moving pipes 132 maybe raised such that the first substrate 210 is held substantiallyparallel to the contact surface of the upper stage 110, as shown in FIG.7.

After the first substrate 210 is held substantially parallel with thecontact surface of the upper stage 110, the second substrate 220 may beheld to a contact surface of the lower stage 120. In one aspect of thepresent invention, the second substrate 220 may be held by the lowerstage 120 by, for example, providing the second substrate 220 on theloader 300, arranging the loader 300 between the upper and lower stages110 and 120, respectively, and arranging the second substrate 220proximate the contact surface of the lower stage 120. Next, the processfor holding the proximately arranged second substrate 220 to the lowerstage 120 may be performed by essentially the same method as describedabove for holding the first substrate 210 to the upper stage 110 and,therefore, a detailed description of such a holding process will beomitted. In another aspect of the present invention, however, the methodby which the second substrate 220 is held to the lower stage 120 may bedifferent from the process described above for holding the firstsubstrate 210 to the upper stage 110. After being held to theirrespective stages 110 and 120, the first and second substrates 210 and220, respectively, may be bonded together.

According to the principles of the present invention, the structure forholding substrates within a substrate bonding apparatus used infabricating LCD devices is beneficial because substrates may besubstantially prevented from sagging without transmitting excessivelylarge, and damaging, suction forces. According to the principles of thepresent invention, suction forces may be effectively transmitted by thestage to operably proximate portions of a substrate. Upon holding asubstrate to a stage, some portions of the substrate (e.g., peripheralportions) may be arranged operably proximate the stage while otherportions of the substrate (e.g., interior portions) may not be arrangedoperably proximate the stage. Therefore, the substrate may appear to sagwith respect to the contact surface of the stage. Accordingly, pads ofthe suction force applying means may be moved operably proximate potionsof the substrate that are sagging to effectively transmit suctionforces. Once suction forces have been effectively transmitted to thesagging portions of the substrate, the pads may be moved such that thesubstrate is held substantially parallel to the contact surface of thestage.

According to the principles of the present invention, excessive suctionforces need not be applied while holding substrates to their respectivestages. Therefore, the substrate may be prevented from sagging whileapplying a suction force that will not damage the substrate.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A structure for holding a substrate within a substrate bondingapparatus, comprising: a stage having a contact surface; at least onepassage arranged within the stage and intersecting the contact surface;a suction force applying means for transmitting a suction force apredetermined distance from the contact surface, wherein the suctionforce applying means is arranged within each passage, and wherein aportion of the suction force applying means is selectively projectablefrom within a respective passage to the predetermined distance from thecontact surface; and a vacuum pump generating the suction force.
 2. Thestructure of claim 1, wherein the suction force applying means includes:a pad having at least one vacuum hole transmitting the suction force toan operably proximate portion of a substrate; a moving pipe in fluidcommunication with the at least one vacuum hole and the vacuum pump,wherein the moving pipe is movable within the passage; and a drivingpart moving the moving pipe within the passage.
 3. The structure ofclaim 2, wherein the at least one passage has first cross-sectionaldimensions; the pad has second cross-sectional dimensions; and thesecond cross-sectional dimensions are smaller than the firstcross-sectional dimensions.
 4. The structure of claim 3, wherein thesecond cross-sectional dimensions are substantially conformal to thefirst cross-sectional dimensions.
 5. The structure of claim 2, whereinthe driving part comprises an actuator; and the moving pipe is an axisof the actuator.
 6. The structure of claim 2, wherein the driving partcomprises a step motor; and the moving pipe is an axis of the motor. 7.The structure of claim 1, further comprising sensing means for measuringa distance between the contact surface and a proximately arrangedsubstrate.
 8. The structure of claim 7, wherein the sensing meanscomprises an interval check sensor.
 9. The structure of claim 1, furthercomprising a plurality of vacuum holes arranged within the stage and influid communication with the vacuum pump transmitting the generatedsuction force from the contact surface.
 10. The structure of claim 1,wherein the stage comprises an upper stage.
 11. The structure of claim1, wherein the stage comprises a lower stage.